Constructors
By definition, a constructor function of some class is a member function that automatically gets implemented whenever an instance of the class to which the constructor belongs comes into existence. The implementation of such a function guarantees that the instance variables of the class will be initialized properly.
A constructor function is unique from all other functions in a class because it is not called using some example of the class, but is invoked whenever we make an object of that class.
A constructor may be overloaded to accommodate many dissimilar forms of initialization for instances of the class. i.e. for a single class many constructors can be written with dissimilar argument lists .